The source of malonyl-CoA in rat heart: The calcium paradox releases acetyl-CoA carboxylase and not propionyl-CoA carboxylase

• Published in: FEBS letters 1986-03, Vol.198 (1), p.47-50
• Main Authors: Scholte, Hans R., Luyt-Houwen, Inez E.M., Dubelaar, Marie-Louise, Huismann, Willem C.
• Format: Article
• Language: English
• Subjects: Acetyl-CoA carboxylase; Acetyl-CoA Carboxylase - analysis; Acyl Coenzyme A - biosynthesis; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Calcium - metabolism; Calcium paradox; Carboxy-Lyases - analysis; Carnitine - analysis; Carnitine O-Palmitoyltransferase - analysis; Carnitine palmitoyltransferase I; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Ligases - analysis; Lyases; Male; Malonyl Coenzyme A - biosynthesis; Malonyl-CoA Propionyl-CoA carboxylase; Methylmalonyl-CoA Decarboxylase; Myocardium - enzymology; Rat heart; Rats; Rats, Inbred Strains
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(86)81182-6

The formation of malonyl-CoA in rat heart is catalyzed by cytosolic acetyl-CoA carboxylase. The existence of this enzyme in heart is difficult to prove by the abundant occurrence of mitochondrial propionyl-CoA carboxylase, which is also able to catalyze the carboxylation of acetyl-CoA. We used the calcium paradox as a tool to separate cytosolic components from the remaining heart, and found that acetyl-CoA carboxylase activity was preferentially released, like lactate dehydrogenase and carnitine, while propionyl-CoA carboxylase was almost fully retained. Acetyl-CoA carboxylase activity was determined after activation by citrate ion and Mg 2+. The activity decreased to 64% by 48 h of fasting.